Container stopper with synthetic resin skin

ABSTRACT

A container stopper, and a manufacturing method therefor, capable of reliably preventing adverse influences of various smells entering from outside the container and absorption and adsorption of the flavor of the contents, as well as preventing adverse influences of a core such as cork. The container stopper comprising a core formed of an elastic material and having a liquid-contact surface and an outer peripheral surface continuous with the liquid-contact surface coated with a skin made of a synthetic resin, and the manufacturing method therefor. In the container stopper, the skin is made of a polyester resin or a synthetic resin having a polyester resin as a main component thereof, and the skin is bonded to the liquid-contact surface and the outer peripheral surface of the core through a bonding layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a container stopper, and amanufacturing method therefor, in which a liquid-contact surface and anouter peripheral surface continuous with the liquid-contact surface of acore formed of an elastic material are coated with a synthetic resinskin.

2. Description of Related Art

As stoppers used for containers of whiskey and wine, for example,compressed cork stoppers, which are formed by blending an adhesive tocork grain made to an appropriate grain size, then heating andpressurizing it to form a compressed cork plate or compressed corkmaterial, and punching or cutting it to a desired shape, and naturalcork stoppers, are widely used conventionally.

However, with the conventional cork stoppers, although surface treatmentis done with wax, silicone oil or the like, the cork is in a bare state.Therefore, when the cork is contaminated by mold smelling substances,typically trichloro-anisole (TCA), they could diffuse into the whiskeyor wine in the containers to spoil the taste of the contents. Inaddition, cork dust could fall into the contents.

Furthermore, the contents could soak into the cells of the cork todiscolor the outer surfaces of the cork stoppers. Where the contentscontain alcohol, lignin and suberin which are components of the corkcould diffuse to the alcohol, causing the cork stoppers to become“thin”, thereby lowering their physical strength and sealing effect.

Also, a container stopper has been proposed in which natural cork orcompressed cork is used as the core of the stopper. The liquid-contactsurface and the outer peripheral surface continuous with theliquid-contact surface of the cork core are coated with a polyethyleneskin. Further, only the liquid-contact portion of the polyethylene skinis coated with a circular sheet made of polyethylene terephthalate (seeU.S. Pat. No. 2,973,249, for example).

According to this conventional technique, the above-mentioned problemsuch as of trichloro-anisole contained in the cork diffusing into thecontents is avoided. However, the flavor of the contents could bespoiled by various types of smells entering from outside the containeror by absorption or adsorption of the flavor of the contents.

That is, although the liquid-contact surface of the core is coated witha sheet of polyethylene terephthalate, the outer peripheral surface,i.e. the portion that contacts the inner peripheral surface of theopening of the container, is coated with a skin of polyethylene. Sincepolyethylene is porous and has a property of absorbing and adsorbingsmell, when stored in a warehouse, closet or the like, mold smellingsubstances, typically TCA, present in such an environment, and smellcomponents such as naphthalene contained in an insecticide, could passbetween the inner peripheral surface of the opening of the container andthe stopper to be absorbed or adsorbed by the polyethylene to adverselyaffect the taste of the contents with the progress of time. Conversely,the flavor of the contents may be absorbed or adsorbed by thepolyethylene, which would adversely affect the taste of the contents.There is room for improvement in this respect.

Naturally, a container stopper, when inserted into the opening of acontainer, is required to have a function for completely preventingleakage of the contents. However, where only the outer peripheralsurface of the core is coated with a skin of polyethylene terephthalateto solve the above-noted problem, a reduction in diameter of the coreinserted into the opening of the container results in “creases” beingformed on the skin of polyethylene terephthalate covering theperipheries. The “creases” become a cause of leakage of the contents.

This invention has been made having regard to the disadvantages of theprior art noted above, and its object is to provide a container stopper,and a manufacturing method therefor, capable of reliably preventingadverse influences of various smells entering from outside the containerand absorption and adsorption of the flavor of the content, as well aspreventing adverse influences of a core such as cork.

SUMMARY OF THE INVENTION

The characteristic construction of the first invention lies in acontainer stopper comprising a core formed of an elastic material andhaving a liquid-contact surface and an outer peripheral surfacecontinuous with the liquid-contact surface coated with a skin made of asynthetic resin, wherein said skin is a skin made of a polyester resinor a synthetic resin having a polyester resin as a main componentthereof, and the skin is bonded to the liquid-contact surface and theouter peripheral surface of said core through a bonding layer.

According to the characteristic construction of the first invention, theliquid-contact surface and the outer peripheral surface continuous withthe liquid-contact surface of the core formed of an elastic material arecoated with a skin made of a polyester resin or a synthetic resin havinga polyester resin as a main component thereof. Even where cork is usedas the core, there is of course no possibility of undergoing adverseinfluences of the core, or adversely affecting the core itself, such asthe taste of the contents being spoiled by diffusion oftrichloro-anisole contained in the cork. Unlike polyethylene, thepolyester resin does not have a property of absorbing or adsorbingsmells, and can therefore prevent adverse influences on the contents byentry of various smells from outside the container and absorption andadsorption of the flavor of the contents.

According to the stopper container of this invention, the skin made of apolyester resin or a synthetic resin having a polyester resin as a maincomponent thereof is bonded to the liquid-contact surface and the outerperipheral surface of the core through a bonding layer. The core and theskin made of a polyester resin or a synthetic resin having a polyesterresin as a main component thereof are completely integrated. Even if thecore reduces in diameter when inserted into the opening of thecontainer, the skin made of a polyester resin or a synthetic resinhaving a polyester resin as a main component thereof follows the core toshrink alike, thereby avoiding “creases”.

As a result, the liquid-contact surface and the outer peripheral surfaceof the core may be coated with the skin made of a polyester resin or asynthetic resin having a polyester resin as a main component thereof,without impairing the functions required of the container stopper. Thisprevents adverse influences on the contents by entry of various smellsfrom outside the container and absorption and adsorption of the flavorof the contents, as well as adverse influences of the core, as notedhereinbefore. Even where the content includes alcohol, alcohol barriercharacteristics of the polyester resin can prevent diffusion of corecomponents to alcohol, to prevent a volume reduction of the core.

The “synthetic resin having a polyester resin as a main componentthereof” herein does not mean that, for example, the polyester resinincluded is in 50% or more, but means that the polyester resin isincluded in an amount sufficient for the above-noted functions andeffects to be expected. This also applies to the description to follow.

The characteristic construction of the second invention lies in thatsaid skin is a skin made of polyethylene terephthalate.

According to the characteristic construction of the second invention,said skin is a skin made of polyethylene terephthalate. Polyethyleneterephthalate has a very high barrier performance, and can furtherreduce the possibility of adverse influences of the core and adverseinfluences on the core itself.

The characteristic construction of the third invention lies in that saidbonding layer is a polyethylene bonding layer.

According to the characteristic construction of the third invention,said bonding layer is a polyethylene bonding layer, which can bond thecore and the skin made of a polyester resin or a synthetic resin havinga polyester resin as a main component thereof to be completely integral,and the core and the skin made of polyethylene terephthalate to becompletely integral.

The characteristic construction of the fourth invention lies in acontainer stopper comprising a core formed of an elastic material andhaving a liquid-contact surface and an outer peripheral surfacecontinuous with the liquid-contact surface coated with a skin made of asynthetic resin, wherein said skin is a skin made of a polyester resinor a synthetic resin having a polyester resin as a main componentthereof, and said core is formed of a synthetic resin having elasticity,said skin being bonded to the liquid-contact surface and the outerperipheral surface of the core by thermal adhesion.

According to the characteristic construction of the fourth invention,the liquid-contact surface and the outer peripheral surface continuouswith the liquid-contact surface of the core formed of an elasticmaterial are coated with a skin made of a polyester resin or a syntheticresin having a polyester resin as a main component thereof. Thus, as inthe first invention described above, adverse influences on the contentby entry of various smells from outside the container and absorption andadsorption of the flavor of the contents can be prevented.

The core coated with the skin made of a synthetic resin also is formedof a synthetic resin having elasticity, and the skin made of a syntheticresin is bonded to the liquid-contact surface and the outer peripheralsurface of the core by thermal adhesion. Thus, the core and skin havingthe same components are bonded to be completely integral. Even if thecore reduces in diameter when inserted into the opening of thecontainer, the skin shrinks alike, thereby avoiding “creases”.

As a result, as in the first invention, the liquid-contact surface andthe outer peripheral surface of the core may be coated with the skinmade of a polyester resin or a synthetic resin having a polyester resinas a main component thereof, without impairing the functions required ofthe container stopper. This prevents adverse influences of varioussmells entering from outside the container and absorption and adsorptionof the flavor of the contents, as well as adverse influences of thecore. Even where the contents includes alcohol, alcohol barriercharacteristics of the polyester resin can prevent diffusion of corecomponents to alcohol, to prevent a volume reduction of the core.

The characteristic construction of the fifth invention lies in that saidskin is bonded in a stretched state to said core.

According to the characteristic construction of the fifth invention,said skin is bonded in a stretched state to the core. This prevents“creases” of the skin which tend to occur with a reduction in diameterof the core when inserted into the opening of the container.

That is, a ratio of diameter reduction of the core inserted into theopening of the container may be set beforehand. Depending on the setvalue, it is not absolutely necessary to bond the skin in a stretchedstate to the core. However, due to variations in the diameter of thecontainer opening occurring at time of manufacture, the core couldreduce in diameter in excess of the set value within the tolerancerange.

In this sense, where said skin is bonded in a stretched state to thecore, even if the core reduces in diameter in excess of the set valuewithin the tolerance range, the skin shrinks only to an extentrestorable to the original state. This improves the performance tofollow the core, thereby to avoid “creases” with increased reliability.

The characteristic construction of the sixth invention lies in that partof an outer surface of said skin located on the outer peripheral surfaceof said core is coated with silicone and/or silicone oil.

According to the characteristic construction of the sixth invention,part of an outer surface of the skin located on the outer peripheralsurface of the core is coated with silicone and/or silicone oil. Thisimproves slipping relative to the container opening whereby thecontainer stopper may be extracted from and inserted into the containeropening smoothly.

Where, for example, a glass container is used as the container,polyethylene terephthalate tends to fit glass, and an unpleasant soundmay be produced at time of extraction and insertion of the containerstopper, or the extraction and insertion may be difficult. By coating anappropriate part of the skin made of polyethylene terephthalate withsilicone and/or silicone oil, no unpleasant sound may be produced, andthe extraction and insertion of the container stopper may be carried outsmoothly.

The remaining parts of the outer surface of the skin located on theouter peripheral surface of the core and not coated with silicone and/orsilicone oil assure sealing of the container with the core, especiallygas barrier performance.

The characteristic construction of the seventh invention lies in that alubricant is added to said silicone and/or silicone oil.

According to the characteristic construction of the seventh invention, alubricant is added to said silicone and/or silicone oil. Even where aglass container is used as the container, the extraction and insertionof the container stopper may be carried out smoothly over a long periodof time.

That is, by coating part of the skin on the outer peripheral surface ofthe core with silicone and/or silicone oil, the container stopper isextracted and inserted smoothly as noted above. However, this effect ismaintained only over a relatively short period of about several months,for example. After a long period, an affinity could develop between thesilicone and/or silicone oil and the glass container to take thesmoothness away from the extraction and insertion of the containerstopper.

Such a possibility is eliminated by adding a lubricant. The extractionand insertion of the container stopper may be carried out smoothly overa long period of time.

The characteristic construction of the eighth invention lies in thatsaid lubricant is one or more substances selected from fatty acidamides, polyhydric alcohol fatty acid esters and their derivatives,particulate polyethylene lubricants, or silicone particles.

According to the characteristic construction of the eighth invention,said lubricant is one or more substances selected from fatty acidamides, polyhydric alcohol fatty acid esters and their derivatives,particulate polyethylene lubricants, or silicone particles. Thisreliably prevents an affinity from developing between the siliconeand/or silicone oil and the glass container to assure smooth extractionand insertion of the container stopper over a long period of time.

The characteristic construction of the ninth invention lies in that thepart of the outer surface of said skin located on the outer peripheralsurface of said core and coated with said silicone and/or silicone oilis surface-treated.

According to the characteristic construction of the ninth invention, thepart of the outer surface of the skin located on the outer peripheralsurface of said core and coated with the silicone and/or silicone oil issurface-treated. Thus, the outer surface of the skin may be coated withthe silicone and/or silicone oil easily and reliably.

The characteristic feature of the tenth invention lies in a method ofmanufacturing a container stopper comprising a core formed of an elasticmaterial and having a liquid-contact surface and an outer peripheralsurface continuous with the liquid-contact surface coated with a skinmade of a synthetic resin, wherein a film of a polyester resin or asynthetic resin having a polyester resin as a main component thereof isused as said skin, the resin film is stretched, and said core ispress-fit in a heated state for extension, the resin film and theliquid-contact surface and the outer peripheral surface of said corebeing bonded through a bonding layer.

According to the characteristic feature of the tenth invention, asynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof is used as the skin forcoating the liquid-contact surface and the outer peripheral surfacecontinuous with the liquid-contact surface of the core formed of anelastic material. The resin film is stretched, and the core is press-fitin a heated state for extension. The film of a polyester resin or asynthetic resin having a polyester resin as a main component thereof iscoated in contact with and firmly on the liquid-contact surface andouter peripheral surface of the core.

In this state, the synthetic resin film of a polyester resin or asynthetic resin having a polyester resin as a main component thereof andthe liquid-contact surface and outer peripheral surface of the core arebonded through a bonding layer. Thus, to manufacture the containerstopper noted hereinbefore, the core and the skin made of a polyesterresin or a synthetic resin having a polyester resin as a main componentthereof are completely integrated.

The characteristic feature of the eleventh invention lies in that asynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof and having a skin-sideadhesion forming layer bonded to an inner surface thereof is used assaid skin, and a core having a core-side adhesion forming layer bondedto a liquid-contact surface and an outer peripheral surface thereof isused as said core, said skin-side and core-side adhesion forming layersbeing integrated by thermal fusion to form said bonding layer.

According to the characteristic feature of the eleventh invention, asynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof and having a skin-sideadhesion forming layer bonded to an inner surface thereof is used assaid skin, and a core having a core-side adhesion forming layer bondedto a liquid-contact surface and an outer peripheral surface thereof isused as the core, said skin-side and core-side adhesion forming layersbeing integrated by thermal fusion to form the bonding layer. Thisprovides a bonding with increased reliability between the core and thesynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof.

Where natural cork or compressed cork is used as the core, a polyesterresin does not necessarily have good adhesion to the cork. By bondingadhesion forming layers to the cork core and the synthetic resin film ofa polyester resin or a synthetic resin having a polyester resin as amain component thereof beforehand, and integrating the two adhesionforming layers by thermal fusion, even where the core is formed of cork,the core and the synthetic resin film of a polyester resin or asynthetic resin having a polyester resin as a main component thereof arebonded reliably.

The characteristic feature of the twelfth invention lies in that saidskin-side and core-side adhesion forming layers are polyethylene layers.

According to the characteristic feature of the twelfth invention, saidskin-side and core-side adhesion forming layers are polyethylene layers.It is therefore possible that the core and the synthetic resin film of apolyester resin or a synthetic resin having a polyester resin as a maincomponent thereof are bonded to be completely integral.

The characteristic feature of the thirteenth invention lies in that asynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof and having a skin-sideadhesion forming layer of polyethylene bonded to an inner surfacethereof by a dry laminate method is used as said skin.

According to the characteristic feature of the thirteenth invention, asynthetic resin film of a polyester resin or a synthetic resin having apolyester resin as a main component thereof and having a skin-sideadhesion forming layer of polyethylene bonded to an inner surfacethereof by a dry laminate method is used as said skin. The syntheticresin film and the skin-side adhesion forming layer are bonded reliablyand firmly. As a result, the synthetic resin film and the core arebonded reliably and firmly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a stopper for whiskey;

FIG. 2 is a view, partly in section, of the stopper for whiskey;

FIG. 3 is an enlarged sectional view of a principal portion of thestopper for whiskey;

FIG. 4 is a perspective view, partly cut away, showing a process ofmanufacturing the stopper for whiskey;

FIG. 5 is a sectional view showing the process of manufacturing thestopper for whiskey;

FIG. 6 is a view, partly in section, of a stopper for wine; and

FIG. 7 is a view, partly in section, of the stopper for wine.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of this invention regarding container stoppers and amanufacturing method therefor will be described with reference to thedrawings.

Container stoppers of this invention are intended for closing openingsof glass or ceramic containers containing liquids including variousalcoholic drinks such as whiskey and wine, and other drinks andcosmetics. A stopper for whiskey, as shown in FIGS. 1 and 2, forexample, includes a circular core 1 section formed of natural cork orcompressed cork which is an example of elastic materials, and having achamfer 1 a at a tip portion and an inner mounting hole 1 b. Aliquid-contact surface F1 and an outer peripheral surface F2 continuouswith the liquid-contact surface F1 of the core 1 are coated with a skin2 of polyethylene terephthalate (PET), which is an example of polyesterresins, having a thickness of about 1-200 micrometers.

As the skin 2 for coating the core 1, the polyethylene terephthalateused, preferably, is an amorphous, relatively flexible polyethyleneterephthalate treated against crystallization by copolymerization with athird component such as 1,4-cyclohexane dimethanol or isophthalic acid.The skin 2 of polyethylene terephthalate is bonded all over theliquid-contact surface F1 and outer peripheral surface F2 of the core 1through a bonding layer 3.

As shown in FIG. 3, the bonding layer 3 mainly comprises a polyethylenelayer, and the polyethylene layer includes a polyethylene adhesive film5 and a polyethylene film 4 arranged in order from adjacent the core 1.A urethane adhesive 6 is interposed between the polyethylene film 4 andthe skin 2 of polyethylene terephthalate.

Further, except a portion of the skin 2 of polyethylene terephthalate,i.e. a portion of the skin 2 located on the outer peripheral surface F2of the core 1, specifically the portion on the chamfer la, the outersurface of the tip portion of the core 1 is coated with silicone 7 overa width indicated by “L” in FIG. 2, in order to be smoothly slidablerelative to the opening of a container not shown.

The coating of silicone 7 on the skin 2 of polyethylene terephthalatemay easily be formed by applying the silicone 7 after surface treatmentby corona treatment or plasma treatment of the surface of the skin 2 ofpolyethylene terephthalate. In this case, it is more desirable to addand apply a lubricant to the silicone 7 than to apply the silicone 7alone.

The lubricant added, preferably, is one or more substances selected fromfatty acid amides, polyhydric alcohol fatty acid esters and theirderivatives, particulate polyethylene lubricants, or silicone particles.The fatty acid amides include, for example, oleic acid amide, erucicacid amide, behenic acid amide, stearic acid amide and so on. Thepolyhydric alcohol fatty acid esters and their derivatives include, forexample, sorbitan monooleate, sorbitan monostearate, sorbitan trioleateand so on.

The stopper for whiskey is formed by inserting a projection 8 aprojecting from a glass umbrella 8 into the mounting hole 1 b of thecore 1, attaching the glass umbrella 8 to the upper end of the core 1 byan adhesive 9, and covering the contact portion of the upper end of thecore 1 and the undersurface of the glass umbrella 8 with a washer seal10 made of a synthetic resin.

To manufacture such a stopper for whiskey, as shown in FIG. 4, a film 2a of polyethylene terephthalate is used as the skin 2 of polyethyleneterephthalate. The polyethylene film 4 is bonded as the polyethylenelayer to the inner surface of the film 2 a of polyethylene terephthalatewith the urethane adhesive 6 by a dry laminate method beforehand.Similarly, the polyethylene adhesive film 5 is also bonded by thermalfusion to the liquid-contact surface F1 and outer peripheral surface F2of the core 1 beforehand.

Next the film 2 a of polyethylene terephthalate is stretched, presseddown at peripheries thereof, and placed in a heated state over the core1, and the core 1 is pressed into a die 11 of smaller diameter than theoutside diameter of the core 1.

Subsequently, when the core 1 is taken out of the die, the core 1restores to its original state whereby the film 2 a of polyethyleneterephthalate is fitted in the stretched state over the core 1.Thereafter thermal fusion is made between the polyethylene adhesive film5 which acts as a core-side adhesion forming layer of the core 1 and thepolyethylene film 4 which acts as a film-side adhesion forming layer ofthe film 2 a of polyethylene terephthalate.

Then, the polyethylene adhesive film 5 and the polyethylene film 4 areintegrated by the thermal fusion. As shown in FIG. 5, the skin 2 ofpolyethylene terephthalate is firmly bonded all over the liquid-contactsurface F1 and outer peripheral surface F2 of the core 1. Subsequently,as noted above, the outer surface of the tip portion of the core 1 iscoated with the silicone 7, and the glass umbrella 8 and washer seal 10are attached to the core 1. The core 1 shown in FIG. 5 is made of asynthetic resin having elasticity.

Although not shown, with the stopper for whiskey shown in FIG. 5, theinner peripheral surface and upper surface of the mounting hole 1 b mayalso be completely coated with the skin 2 of polyethylene terephthalate.In this case, the core 1 will be completely sealed off from the exteriorto eliminate adverse influences of the core 1 on the contents.

While the stopper for whiskey has been described above, the same appliesto other stoppers. In the case of a stopper for wine, as shown in FIGS.6 and 7, a solid circular core 1 section having a chamfer 1 a at a tipend portion thereof is formed of natural cork or compressed cork. Thecore 1 includes a liquid-contact surface F1 and an outer peripheralsurface F2 continuous with the liquid-contact surface F1 which arecoated all over with a skin 2 of polyethylene terephthalate having athickness of about 1-200 micrometers. The skin 2 may have a coatingboundary adjacent the center of the core 1 as shown in FIG. 6, or mayhave a coating boundary at an end of the core 1 as shown in FIG. 7.

What is preferred as the skin 2 is an amorphous, relatively flexiblepolyethylene terephthalate treated against crystallization bycopolymerization with a third component such as 1,4-cyclohexanedimethanol or isophthalic acid. As in the stopper for whiskey describedhereinbefore, the skin 2 of polyethylene terephthalate is bonded allover the core 1 through a bonding layer 3 mainly comprising apolyethylene layer.

The manufacture of the stopper for wine is the same as the manufactureof the stopper for whiskey described above, and a detailed descriptionwill not be made to avoid tautology. A film of polyethyleneterephthalate with a polyethylene film bonded to the inner surfacethereof, and a core 1 with a polyethylene sheet bonded to the entireouter surface thereof, are used. The film of polyethylene terephthalateis stretched, pressed down at peripheries thereof, and placed in aheated state over the core 1, and the core 1 is pressed into a die ofsmaller diameter than the core 1.

As a result, the film of polyethylene terephthalate is fitted in thestretched state over the core 1. The polyethylene adhesive film 5 on thecore 1 and the polyethylene film 4 on the film of polyethyleneterephthalate are integrated by thermal fusion to form the bonding layer3. The skin 2 of polyethylene terephthalate is bonded all over the core1.

Further, the stopper for wine usually is not something that isrepeatedly pulled out of and put into the opening of the container. Theembodiment shown in FIGS. 6 and 7 does not include the skin of silicone7 provided for the stopper for whiskey.

Other Embodiments

(1) In the foregoing embodiment, the core 1 is formed of natural cork orcompressed cork. Apart from cork, various elastic materials havingappropriate elasticity required for the core of a stopper for acontainer may be used, which include natural rubber, synthetic rubber,molding of wood chips, a polyester resin, and a synthetic resin having apolyester resin as a main component thereof.

Regarding the skin 2 for coating the core 1, an example is shown asbeing formed of polyethylene terephthalate which is one example ofpolyester resins. Apart from this, polybutylene terephthalate, polyesterresins such as thermoplastic polyester elastomer, and various syntheticresins having polyester resins as main components thereof, may be used.

The bonding layer 3 is shown to comprise mainly a polyethylene layer.Apart from this, the bonding layer may be formed, for example, ofpolyolefine, TPO, TPEE, TPU, and so on.

(2) In the foregoing embodiment, for bonding the core 1 and the skin 2of polyethylene terephthalate, the polyethylene adhesive film 5 andpolyethylene film 4 are bonded to the core 1 and skin 2 beforehand, andthe polyethylene adhesive film 5 and polyethylene film 4 are integratedby thermal fusion to form the bonding layer 3. The bonding layer 3 maybe formed by methods other than thermal fusion. Where the polyethyleneadhesive film 5 and polyethylene film 4 are bonded beforehand, theadhesive used may be, apart from the polyethylene or urethane adhesive,various adhesives such as a polyester adhesive, a silicone adhesive andan epoxy phenol adhesive, for example.

(3) In the foregoing embodiment, an example is shown in which silicone 7is used in the stopper for whiskey, and silicone 7 is not used in thestopper for wine. Instead, silicone 7 may not be used in the stopper forwhiskey, and silicone 7 may be used in the stopper for wine.

In any case, where the silicone 7 is used, the silicone 7 may bereplaced with silicone oil, or the silicone 7 and silicone oil may beblended for use.

The container stoppers and the manufacturing method therefor accordingto this invention are applicable as container stoppers for closingopenings of glass or ceramic containers containing various alcoholicdrinks such as whiskey and wine, various non-alcoholic drinks, andvarious liquids such as cosmetics, and as methods of manufacturing thecontainer stoppers.

1. A container stopper comprising a core formed of an elastic materialand having a liquid-contact surface and an outer peripheral surfacecontinuous with the liquid-contact surface, both the liquid-contactsurface and the outer peripheral surface being coated with a skin madeof a synthetic resin, wherein said skin is a skin made of a polyesterresin or a synthetic resin having a polyester resin as a main componentthereof, said skin being bonded to said core via a bonding layer; saidbonding layer includes a core-side adhesion forming layer bonded to theliquid-contact surface and the outer peripheral surface and a skin-sideadhesion forming layer bonded to the skin; and said skin is bonded tothe core by thermal fusion of the core-side adhesion forming layer andthe skin-side adhesion forming layer.
 2. The container stopper asdefined in claim 1, wherein said skin is a skin made of polyethyleneterephthalate.
 3. The container stopper as defined in claim 1, whereinboth said skin-side adhesion forming layer and said core-side adhesionforming layer are polyethylene bonding layers.
 4. The container stopperas defined in claim 1, wherein said core is formed of a synthetic resin.5. The container stopper as defined in claim 1, wherein said skin isbonded in a stretched state to said core and said skin maintains thisstretched state after its bonding to the core.
 6. The container stopperas defined in claim 5, wherein part of an outer surface of said skinlocated on the outer peripheral surface of said core is coated with atleast one of silicone and silicone oil.
 7. The container stopper asdefined in claim 6, wherein a lubricant is added to said at least one ofsilicone and silicone oil.
 8. The container stopper as defined in claim7, wherein said lubricant is at least one of substances selected fromfatty acid amides, polyhydric alcohol fatty acid esters and theirderivatives, particulate polyethylene lubricants, and siliconeparticles.
 9. The container stopper as defined in claim 6, wherein thepart of the outer surface of said skin located on the outer peripheralsurface of said core and coated with said at least one of silicone andsilicone oil is surface-treated.
 10. The container stopper as defined inclaim 2, wherein said skin is bonded in a stretched state to said coreand said skin maintains this stretched state after its bonding to thecore.
 11. The container stopper as defined in claim 3, wherein said skinis bonded in a stretched state to said core and said skin maintains thisstretched state after its bonding to the core.
 12. The container stopperas defined in claim 4, wherein said skin is bonded in a stretched stateto said core and said skin maintains this stretched state after itsbonding to the core.
 13. The container stopper as defined in claim 1,wherein said skin is a polyethylene terephthalate skin formed as acopolymer with 1,4-cyclohexane dimethanol or isophthalic acid.
 14. Thecontainer stopper as defined in claim 13, wherein said skin is bonded ina stretched state to said core and said skin maintains this stretchedstate after its bonding to the core.